Three auto 4x4 light trucks for 2019

It’s always amazed us that working-4x4 ute and light truck makers have stuck with manual transmissions, when all earthmoving gear and most heavy all-wheel drive trucks have automatic transmissions.

Thankfully, that scene is changing and there will be three self-shifting light 4x4 trucks available in 2019.

The immediate choice is Isuzu’s market-leading Isuzu NPS300 4x4 that has just been released with the company’s automated manual transmission (AMT).

Another factory-fitted AMT 4x4 light truck will come from Iveco, in the form of the 2019 Daily 4x4 that we covered in October 2018. There’s no official release date for this van and cab/chassis range as yet, but we reckon the Australian Iveco organisation is champing at the bit for the upgraded model, with its optional eight-speed self-shifter.

AMT models normally attract an RRP increase in the $3000-$4000 band.

The third entrant into the self-shifting 4x4 light truck market is Hino’s 817 4x4, but there’s no factory-auto-fitment for this truck as yet. But there is an Allison after-market automatic transmission kit available from Penske and I was lucky enough to test drive the prototype vehicle.

First up, some background into 4x4 light truck two-pedal drivelines.

Isuzu and Iveco have adopted automated manual transmissions for their 4x4 light trucks for two main reasons: lower cost than a torque-converter transmission and reduced torque loading in the driveline.

Torque loading is a significant issue with 4x4s, because the transfer case low-range ratio multiplies transmission torque by up to 3:1 in most cases. That’s a lot of torque loading going into propeller shafts, differentials and half shafts.

In the case of a torque converter automatic transmission, such as an Allison, there’s additional torque multiplication by the fluid coupling’s stator – typically 2.5:1 – and the transfer case may not have the torque capacity to handle that additional torque loading.

Most automated manual transmissions don’t have that torque multiplication. In the case of Isuzu’s NPS300 AMT that does have a fluid coupling there’s no stator in the coupling, so there’s no torque increase.

The Hino 817 4x4 is a different beast from its competitors, in that it employs the large transfer case from the company’s GT, 13-tonnes GVM truck, so there’s ample torque capacity in the transfer case to handle more than double the 817’s engine torque peak of 464Nm. Hence, it can accept a torque-converter fully-automatic transmission.

Penske Power Systems and Hino let me evaluate the first automatic transmission fitment to the Hino 817 4x4 truck.

The retro-fit gearbox project was the brainchild of Penske’s Allison Transmission sales specialist, John Rapinette. John is no ordinary sales person, having grown up in the school of hard knocks at Bob Whitehead’s RFW truck factory, when that brand offered by far the best off-road truck range in Australia.

RFWs came standard with Allison transmissions, when nearly all other European, Japanese and North American 4x4, 6x6 and 8x8 machines had manual boxes.

When John Rapinette saw the Hino 817 4x4 he just knew it needed an automatic transmission option, so he worked with Penske’s engineering team on the project.

What makes the Hino most suitable for an Allison transplant is the fact that it uses the heavy duty transfer case from the 13-tonnes-GVM Hino GT. Torque capacity is much higher than competitive-truck two-speeds, so the Allison 1000’s torque converter 2:1 stall ratio – doubling converter engagement torque – posed no problems for the transfer case.

Designed for light commercial vehicles in both on-highway and public transport applications, Allison Transmission’s 1000 and 2000 Series are rated up to a maximum of 224kW (300hp) and have up to six speeds available, including two overdrives. Both close and wide ratio gearing are offered.

The addition of fifth-generation electronic controls enhance operation and diagnostics capability. Additionally, provisions such as turbine-driven Power Take-Off (PTO) with optional neutral lock-up and a parking pawl are available.

Fitting the auto in place of the standard manual box required some adaptation; including reworking the shift quadrant and making up a custom rear mount and a jackshaft to the centrally-mounted transfer case.

The box in the evaluation truck was set up as a single-overdrive five-speed, with the parking pawl option and with ‘power’ and ‘economy’ shift programming. It had a car-like ratio selector module, with ‘P’, ’N’ and ‘D, 3, 2, 1’ positions. Anyone with a car automatic transmission driving background would feel at home in the Hino 817 4x4 auto.

The test truck was loaded to seven tonnes GVM and I drove it on freeways, secondary bitumen, gravel and on bush trails.

Allison’s electronically controlled units shift smoothly and the 1000 is no exception. Shift quality was car-like, up and down the box. Additionally, when the exhaust brake lever was activated, the transmission went into a downshift program that kept engine revs high, to improve retardation. I found retardation on and off road almost the equal of the manual-box truck.

It was only on very steep downhill descents, with the transmission locked in first gear that I noticed less engine braking than the manual box provides in low-low.

It’s possible to drive the 1000 as a torque-converter manual box, but I tested it mainly in the ‘D’ position and discovered that the auto box is probably smarter than most drivers – myself included. Only when tightly manoeuvring and in steep off-road situations did I feel the need to lock the box in first gear.

I reckon there’s no need for the ‘power’ and ‘economy’ switch, because the loaded truck performed very well in ‘economy’. Also, it can be re-programmed as a six-speed, but I felt that a single overdrive, with legal cruising speed revs just over 2000rpm was fine for this weight.

That’s the good news. The not-so-good news is the cost: around 20 grand. That could be defrayed somewhat by selling the manual main transmission that, ironically, is an Isuzu-manufactured six-speed box.

Most two-pedal-control 4x4 light truck buyers will opt for the lower-cost Isuzu and Iveco AMT machines, but there are some low-speed, high-load vocations where the torque-converter Allison box will have the edge.